1. Field of the Invention
The present invention relates generally to an electromechanical cylinder lock and, in particular, to a cylinder lock in which an electrical actuator is employed to provide access to the lock cylinder.
2. Description of Related Art
Electromechanical locking devices are known which include electrically interfaced or controlled release mechanisms for operating a lock cylinder. For example, U.S. Pat. No. 4,712,398 discloses an electronic locking system comprising a lock cylinder with a rotatable plug located therein. An electronically activated release assembly is provided which selectively disengages a locking pin from the plug to allow turning of the key to rotate the plug relative to the cylinder. The lock cylinder and key each include an electronic memory device containing keying system codes. Upon insertion of the key the release mechanism disengages the locking pin from the plug to allow its rotation. U.S. Pat. No. 5,552,777 discloses another type of electromechanical cylinder lock having a blocking pin and an electromagnetic solenoid in the cylinder plug. The blocking pin extends into a recess in the cylinder shell, and is retracted upon actuation of the solenoid by a microprocessor in the key.
One benefit of including electronic control features in locks is the ability to provide increased keying codes for operating the lock. For example, information can be stored in the lock and/or key such that the locking mechanism is activated in response to detecting and/or exchanging data. As the information stored in the components may be altered, it is possible to vary the keying codes without changing the system hardware. In contrast, changing the mechanical keying codes in a purely mechanical lock typically requires forming a new key with different bitting surfaces, a more involved process than reprogramming electronic components of an electromechanical lock.
Despite progress made in the development of prior art electromechanical locking systems, several deficiencies exist which leave room for improvement. For example, prior art systems do not provide the ability to retrofit a purely mechanical lock to form an electromechanical lock which is operated at least in part by information stored in a key and/or lock cylinder. The benefits of retrofitting a mechanical lock in this manner include preventing the need to alter the keying of the lock should it become necessary to change the combination, for example when an employee loses his or her key or leaves an establishment. In such a case, the components of the lock may be reprogrammed to change the keying codes to prevent the employee's key from operating the lock. Additionally, prior art systems using electromagnetic components such as solenoids have been found to be impractical, because of the small space available and the relatively large size of components needed to develop enough force to release the blocking mechanism. Accordingly, there remains a need in the art for an improved electromechanical cylinder lock system.